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Biomedical subjects

J Pastor

Publications and source records attributed to J Pastor.

140 records · Page 8Linked to original sources
PubMedDate not supplied

[Biophysical foundations of magnetoencephalograhy].

OBJECTIVE: It is sought to expose in a simple but rigorous way the physical, neurobiological and methodological foundations of the magnetoencephalography (MEG). DEVELOPMENT: We start from the basic properties of the classical electromagnetism, analyzing in detail the concepts of electric and magnetic fields, the Maxwell s equations and the multipolar development of potentials. All these tools are very important to know the peculiarities of the MEG studies. Later on, they are reviewed very briefly the different types of potentials generated by the neurons and their implication in the MEG. Lastly, some necessary technical characteristics will be commented for detection of the very weak neuromagnetic fields. It is shortly exposed the concept of tunnel effect, in one that detection systems used at the present time are based (SQUID). CONCLUSION: MEG is a very promising recent technique that is used in epilepsy studies, evoked potentials and other functional pathologies. Its utility in clinic continues being even controversial. However, it is fundamental to know the mechanisms that justify their use in order to know better their benefits and limitations.

Action Potentials↗
PubMedDate not supplied

[Voltage sources analysis in studies with foramen ovale electrodes].

INTRODUCTION: Paroxysmal activity in medial temporal lobe epilepsy is originated in either hippocampal or parahippocampal regions. This activity can be directly recorded by foramen ovale electrodes. That paroxysmal activity will start from irritative or ictal areas. However, anatomo-functional relations between both regions are still debated. OBJECTIVE: We describe a new physical very simple model which allows to directly analysis the anatomo-physiological relations between sources for interictal and ictal areas. RESULTS: 1) The mathematical model allows to fit with minimum error and great precision the voltage sources originated from monopoles. 2) We can obtain this degree of precision with a matrix using an internodal distance of 0.1 mm (300x200 nodes) 3) Triplets of potentials with double sources with equal or specially with inverse charges have bigger error than monopolar charges. 4) Fitting real data obtained from a patient shows an error of 0.29 +/- 0.17% for interictal and 0.54 +/- 1.22% and 2.84 +/- 3.00% for two seizures (mean +/- SD). CONCLUSIONS: This model allows directly to know the relative anatomo-physiological relations between interictal and ictal sources in MTLE, which have a very important implications so for patho-physiological as therapeutics and outcome implications.

Action Potentials↗
PubMedDate not supplied

[Treatment of a case of essential tremor with subthalamic stimulation].

INTRODUCTION: Chronic stimulation of the subthalamic nucleus (STN) has proved itself to be useful in treating Parkinson's disease and especially in dealing with the tremor suffered by patients. Yet there is very little experience to support the use of STN as an alternative therapy in non Parkinsonian tremors. CASE REPORT: Our study considered the case of a patient who had been diagnosed as suffering from drug resistant essential tremor which was predominant in the distal region of the upper right limb and was treated by unilateral stimulation of the STN. RESULTS: The patient's clinical state improved significantly from the first weeks onwards. After a year and a half of therapy, the patient had achieved a stable improvement of 82.4% on the tremor scale and medication was reduced by 41.7%. CONCLUSIONS: SNT stimulation appears as a suitable target for the treatment of drug resistant essential tremor.

Aged↗
PubMedDate not supplied

[Psychosurgery and the neurosurgical treatment of pain: a systematic review of the experience gained in these kinds of treatment].

INTRODUCTION: Psychosurgery and the neurochemical treatment of pain (NTP) are therapeutic options restricted to patients who show resistance to medical treatments. Surgical techniques have been perfected over the last few decades. AIMS: Our aim was to conduct a systematic review of the studies dealing with psychosurgery and NTP reported in the literature, based on the standards of quality used in evidence-based medicine. DEVELOPMENT: Following screening and selection, nine of the 178 papers found (MEDLINE, 1990-2002) were selected for the study: three referring to the treatment of neuropathic pain and six about the treatment of obsessive-compulsive disorder (OCD). The objectives were the therapeutic results in all cases, the study of the anatomical-functional bases in three of them and the description of side effects in five. After adapting the standards of quality used in evidence-based medicine (there are no standards for papers about surgery), one was classified in group B, six in group C and two as C-D. The three papers about the treatment of pain reported a significant improvement in the pain scales in 40-77% of patients. As regards the treatment of OCD, results showed an overall improvement of the scales in 20.4-70% of the patients with an improvement above 50%. The side effects are also described. CONCLUSIONS: Data published support the indication of psychosurgery and NTP for selected patients with neuropathic pain and OCD. The methodological limitations of the papers prevent us from drawing conclusions about the other diseases for which these techniques have been indicated.

Diagnosis, Differential↗
PubMedDate not supplied

[Pharmacoresistant temporal-lobe epilepsy. Exploration with foramen ovale electrodes and surgical outcomes].

AIM: To report our experience in the surgical treatment of temporal-lobe epilepsy. PATIENTS AND METHODS: An analysis was performed of the outcomes of 137 patients submitted to surgery between 1990 and 2001, with a follow-up of more than two years. A study was conducted of the percentages of successful detection by the different complementary tests--MRI, EEG, interictal SPECT, video-EEG with foramen ovale electrodes (FOE), neuropsychological study (NPS)--and the precision with which they reported the epileptogenic focus. RESULTS AND CONCLUSIONS: Successful surgical outcomes (Engel grades I-II): 73.4%. No surgical mortality occurred, although some mild, reversible morbidity was observed. Surgical outcomes were not affected by sex, age, age of onset and the length of time the patient had had the disease, or the frequency of the seizures. No association was found between seizures in the immediate post-operative period and a poorer long term control of the epilepsy. MR images were normal in 25% of patients; in these cases the surgical outcomes (Engel grades I-II at two years: 62%) were significantly poorer than in cases of tumours/cavernomas (86%); RMI studies of other types of lesions gave intermediate results (72%). With respect to the capacity of the different tests to lateralise/locate the epileptogenic focus, video-EEG-FOE proved to be the best, followed by MRI, SPECT, EEG and NPS.

Adolescent↗
PubMedDate not supplied

[Impact of experience on improving the surgical outcome in temporal lobe epilepsy].

INTRODUCTION: Recently, we have published the results of a first surgical series of patients with temporal lobe epilepsy (TLE). We describe a posterior series of patients intervened of TLE, we compare the functional results with the previous series and we finally analyze the causes of changes. PATIENTS AND METHODS: We studied the first 22 consecutive patients surgically intervened of TLE with a minimum post-surgery follow-up of 2 years. Patients showing I and II Engel's grade were used as gold standard for evaluation of pre-surgical complementary studies. RESULTS: We have obtained better functional results: 91% patients showing Engel's grade I, 9% showing grade II and neither III nor IV grades were obtained. Pre-surgical studies changed in comparison with the previous report. The most improving change was observed in video-EEG with foramen-ovale electrodes (FOE) (37%), scalp EEG (26.6%), interictal SPECT (11.7%) and MRI (11.7%). Video-EEG with FOE was the study than showed greater concordance with epileptic focus (95.5%), followed by EEG (86.4%). In 35% of cases, MRI was normal or without valid data for correct localization of focus. CONCLUSIONS: Video-EEG with FOE and TLE surgery are safety methods, which results improve with the experience. Normal or not informative MRI do not should a priori reject those patients with drug-resistant TLE from surgery.

Adolescent↗
PubMedDate not supplied

[The pathophysiological foundations of temporal-lobe epilepsy: studies in humans and animals].

INTRODUCTION: Temporal lobe epilepsy (TLE) is the most frequent form of pharmaco-resistant epilepsy in human. Research using material from TLE patients undergoing surgery and animal models has significantly increased in the last decade. DEVELOPMENT: We review recent findings obtained over the last years from electrophysiological and anatomical studies in human and animal models of TLE. Data suggest a large heterogeneity and inter-individual variability depending on the model and the system under study. However, a common principle that appears to underlie the epileptic condition is the reorganization of excitation and inhibition resulting in hyperexcitability. Recent research combining in vitro electrophysiology together with depth recordings in vivo and new analytical methodologies is also discussed. CONCLUSIONS: A multidisciplinary approach using both human and animal models can help to fill gaps in our knowledge and to provide unique insights into the pathophysiology of TLE.

Animals↗
PubMedDate not supplied

[Changes in cerebral calcium, sodium and potassium after single or repeated administration of lithium in the rat].

A single administration (IP) of lithium chloride in the rat induces a decrease in erythrocyte calcium, proportional to the lithium level (p less than 0.01) and a diminution in cerebral calcium (p less than 0.001) which is accompanied by decrease in cerebral sodium and potassium levels (p less than 0.001). Repeated administration (IP + VO) has the same cerebral effects. The authors report that the reversible decrease in calcium, sodium and potassium, resulting from an increase in cerebral lithium levels, can be demonstrated on sampling at 1.30 and 3 hours (IP), or at 12 hours (VO). These results are relevant to the treatment of manic illnesses using calcium antagonists.

Administration, Oral↗
PubMedDate not supplied

[Renal adenocarcinoma with vena cava invasion: current status of its diagnosis and treatment using total segmentary cavectomy].

OBJECTIVES: Renal adenocarcinoma is characterized by marked venotropism; 20-49% show extension into the main renal vein and 4-19% into the vena cava. The present study analyzes the different diagnostic methods to evaluate the vascular involvement by renal carcinoma and presents the results achieved by total segmental cavectomy with ligation of the left renal vein and without vena caval reanastomosis. METHODS: Three patients (two males, one female) underwent total segmental cavectomy with ligation of the left renal vein in our Service over the last 10 years. A bilateral subcostal approach with access to the large vessels was utilized in all three cases. The superior and inferior renal vena cava were exposed and the hepatic veins were ligated at the level of the intrahepatic segment. Incision of the vena cava was performed, the thrombus was removed and the renal vessels were ligated. The proximal and distal segments of the vena cava were ligated after cavectomy. In the third patient, intrahepatic extension of the thrombus required the use of a temporary filter for the proximal segment of the vena cava. RESULTS: The early postoperative course was satisfactory; adequate renal function was maintained and no problems with venous return were observed. Of the diagnostic methods analyzed, MRI was found to be the most useful. A relationship was found between survival and the pathological stage and the presence or absence of lymph node metastasis. CONCLUSIONS: Total segmental cavectomy without reanastomosis and with ligation of the left renal vein appears to be a feasible technique which achieves good results. MRI is the diagnostic method of choice in the evaluation of vascular tumor extension.

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